From: Cedric Le Goater <clg@fr.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Stewart Smith <stewart@linux.vnet.ibm.com>,
skiboot@lists.ozlabs.org, benh@au1.ibm.com,
linuxppc-dev@lists.ozlabs.org,
Neelesh Gupta <neelegup@linux.vnet.ibm.com>
Subject: Re: [PATCH v3 3/3] powerpc/powernv: remove opal_sensor_mutex
Date: Mon, 30 Mar 2015 08:51:04 +0200 [thread overview]
Message-ID: <5518F258.4060308@fr.ibm.com> (raw)
In-Reply-To: <1427681398.4218.7.camel@ellerman.id.au>
On 03/30/2015 04:09 AM, Michael Ellerman wrote:
> On Fri, 2015-03-27 at 17:39 +0100, Cédric Le Goater wrote:
>> The opal sensor mutex protects the opal_sensor_read call which
>> can return a OPAL_BUSY code on IBM Power systems if a previous
>> request is in progress.
>>
>> This can be handled at user level with a retry.
>
> It can, but how does it actually look in practice?
>
> It looks like the only use of opal_get_sensor_data() is show_sensor() in
> drivers/hwmon/ibmpowernv.c.
>
> Because that's a sysfs attribute folks will be generally just dumping
> that with cat, or reading it in a shell script, neither of which will
> cope nicely with EBUSY I think?
It won't, I agree but it should only happen when running concurrent cat
commands on the hwmon sysfs files. The event should be rare enough.
Anyhow, this is not a big issue. We can drop that patch. The real "issue"
is the time it takes to get some values back from the FSP. This is what
user space has been most surprised about.
Thanks,
C.
next prev parent reply other threads:[~2015-03-30 6:51 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-25 17:50 [PATCH] powerpc/powernv: handle OPAL_SUCCESS return in opal_sensor_read Cédric Le Goater
2015-03-25 23:07 ` Stewart Smith
2015-03-26 9:44 ` Cedric Le Goater
2015-03-26 12:58 ` Cedric Le Goater
2015-03-26 16:04 ` [PATCH v2 1/3] powerpc/powernv: convert codes returned by OPAL calls Cédric Le Goater
2015-03-26 16:04 ` [PATCH v2 2/3] powerpc/powernv: handle OPAL_SUCCESS return in opal_sensor_read Cédric Le Goater
2015-03-26 16:04 ` [PATCH v2 3/3] powerpc/powernv: remove opal_sensor_mutex Cédric Le Goater
2015-03-27 9:59 ` [v2,1/3] powerpc/powernv: convert codes returned by OPAL calls Michael Ellerman
2015-03-27 10:36 ` [Skiboot] [v2, 1/3] " Benjamin Herrenschmidt
2015-03-27 10:39 ` Cedric Le Goater
2015-03-27 10:45 ` [v2,1/3] " Cedric Le Goater
2015-03-27 16:39 ` [PATCH v3 1/3] " Cédric Le Goater
2015-03-30 2:05 ` Michael Ellerman
2015-03-30 6:37 ` Cedric Le Goater
2015-03-30 6:54 ` Michael Ellerman
2015-03-30 6:56 ` Cedric Le Goater
2015-03-30 10:06 ` [PATCH v4 1/2] " Cédric Le Goater
2015-03-30 10:06 ` [PATCH v4 2/2] powerpc/powernv: handle OPAL_SUCCESS return in opal_sensor_read Cédric Le Goater
2015-03-27 16:39 ` [PATCH v3 2/3] " Cédric Le Goater
2015-03-27 16:39 ` [PATCH v3 3/3] powerpc/powernv: remove opal_sensor_mutex Cédric Le Goater
2015-03-30 2:09 ` Michael Ellerman
2015-03-30 6:51 ` Cedric Le Goater [this message]
2015-03-30 6:59 ` Michael Ellerman
2015-03-30 10:05 ` Cedric Le Goater
2015-03-27 6:05 ` [PATCH] powerpc/powernv: handle OPAL_SUCCESS return in opal_sensor_read Stewart Smith
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